HEMIPTEEA. 117 



It is in the froth that the larvae change into pupae, and do not leave 

 their habitation to undergo their final metamorphosis. They have 

 then, says De Geer, the art of causing the froth inside to evaporate 

 and dry up, in such a manner as to form a space inside the mass 

 of froth, in which their bodies are entirely free. The exterior froth 

 forms a roof closed in on all sides, under which the insect lies 

 quite dry. 



In this vaulted cell, the pupa disengages itself little by little 

 from its skin, which first splits up along the head, and then on 

 the thorax. This opening is sufficiently large to enable it to 

 come out of its envelope. It is in the month of September that 

 these insects are particularly abundant, when the trees and plants 

 are covered with them. Sometimes the froth drips off, like a sort 

 of small rain, from branches which are covered with it. Towards 

 the autumn the females are gravid. They are then so heavy, 

 that they can hardly jump or fly. The males, on the contrary, 

 make prodigious bounds; they throw themselves sometimes 

 forward to a distance of more than two yards. They are very 

 difficult to catch, and still more difficult to find again when one 

 has once let them escape. And so Swammerdam calls these in- 

 sects Sauterelles- Puces (Flea- Grasshoppers), 

 because they jump like fleas. 



All that we have said relates to the Cercopis 

 spumaria, or Froghopper (Fig. 85), an insect 

 common all over Europe, and which Geoflroy 

 calls the Cigale bedeaude. 



"It is of a brown colour," says Geoffroy, " often rather greenish. 

 Its head, its thorax, and its elytra, are finely dotted ; on these last 

 one sees two white oblong spots. The lower part of the insect 

 is light brown." 



We will mention, as it belongs to the group with which we are 

 now occupied, a noxious insect, the Jassus devastatans, which since 

 1844 seems to have taken up its quarters in the commune of Saint 

 Paul, in the department of the Basses-Alpes. It sucks the 

 leaves and stalks of cereals, causing them to wither, and may be 

 found even in winter on young corn, but principally in the spring. 



* " Histoire abregee des Insectes, dans laquelle ces animaux sont ranges dans un 

 ordre methodique." In 4to, au VII. de la Republique, tome i. p. 416. 



